For example, some motorcycles have a transmission mechanism for changing the engaged state of a plurality of gears (e.g., see Japanese Patent Laid-Open Publication No. JP 2004-203313). The transmission mechanism has a rotation drum. The transmission gear ratio of the transmission mechanism is changed according to the rotating position of the rotation drum.
JP 2004-203313 discloses a structure that detects the rotating position of a rotation drum by detecting the contacting position of a conductive wire that is a rotor rotated together with the rotation drum.
However, in the structure described in JP 2004-203313, the rotor is fixed to the rotation drum, which requires a space around the rotation drum. This results in the low degree of freedom of the design. In addition, the relative positional relation between the rotor and the detector detecting the rotor is likely to vary. This is likely to cause a detection error.
The rotation detecting device including the rotation drum also has the above problem when detecting the rotating position of a member other than the rotation drum.
In view of the above circumstances, an object of the present invention is to provide a rotation detecting device that can make the degree of freedom of the design of members higher and can easily improve the detection accuracy of a rotation member to be rotation-detected.